Rear disk brakes??
 

Last weekend while at scrap busters (the local u pull it) I came across a 4dr..I believe 4x4 with rear disk brakes. Immediately I was intrigued due to the simplicity and benefit of disk as opposed to drum...but a better question is...are there any differences, severe mods to be performed, unknown benefits or disadvantages in taking advantage of what I've found? Also what's so special about that particular year that they got the disk setup and why has it now been discontinued?

both of my 98's have rear disc brakes. i dont know why you wouldnt have them on your 03...

Disk breaks are prefered for their ease of maintenance and better stopping power. I believe you run into issues with the ebrake while doing the swap to disk brakes but there are ways to remedy this. If you are going to go thru the hassle of an axle swap I would say ditch the blazer axle all together (unless you can find a zr2 axle) and find a ford 8.8 out of an Explorer. They are just a far stronger axle all around and are a direct bolt in for the Blazer except the ebrake cable again! You also have to remember that you have to find a rear axle that matches the gearing you have now to keep it the same as the front or you will have major problems the first time you try to use 4wd.

If you're thinking of swaping the axle, you will need to pull the park brake cable as well. The cable from your drum brakes is not compatible without doing some fabrication, and it would be a lot easier to just pull the cable. You will also need the hard lines for the brakes. Other than that it is a very easy swap. I changed mine out in a couple of hours by my self in the driveway.

If you're going to be lifting your Blazer and putting tires bigger than 31's on it then like Rex said, you might want to look for a stronger axle than the stock 4x4 S-series axle. The ZR2 8.5 rear end is another good choice for a moderate off-road machine. Be sure to match gears front and rear in your truck.